textproduct: Albany

WHAT HAS CHANGED

Wind Advisory upgraded to High Wind Warning for northern and central Taconics, Bennington County Vermont and Berkshire County Massachusetts due to a period of wind gusts late tonight into Friday morning which will top out around 60 mph.

KEY MESSAGES

1. Near record breaking temperatures expected on Friday morning ahead of a strong cold front. Periods of moderate rainfall will accompany the front and there is the possibility of a rumble of thunder as well.

2. There is the possibility for some urban and poor drainage flooding due to the rain and snowmelt early Friday, but main stem river flooding is not expected.

3. Strong southerly wind gusts are likely tonight into Friday morning, especially for high terrain areas of the Taconics, Berkshires and southern Greens, which may result in downed trees and power lines. Strong westerly wind gusts are expected across the entire area Friday afternoon into late Friday evening.

4. Colder temperatures return this weekend into early next with a chance for widespread accumulating snowfall on Tuesday.

DISCUSSION

KEY MESSAGE 1... A strong area of low pressure is moving across the Upper Midwest and will be crossing the upper Great Lakes this evening. This area of low pressure will move across Ontario tonight and head across Quebec on Friday. This frontal system will drag a cold front across the region on Friday, mainly during the mid morning through early afternoon hours.

Ahead of this storm system, a strong low-level jet will be in place. At 850 hpa, southerly winds will reach 50-80 kts, which is about about 2-3 STD above normal. At the surface, southerly winds are already in place well ahead of this system and surface temps are in the 40s in many areas. While temps may initially drop a little bit this evening, the increasing clouds and persistent southerly flow will allow for temps to hold steady or start to rise, especially by the late night hours. Temperatures will reach the mid to upper 40s for the high terrain and low to mid 50s for the valley areas for shortly after sunrise on Friday. This will be near record-breaking warmth for mid December (the daily record for Albany is 54 set in 1895). Friday's max temps will be in the morning hours, as once the front crosses, temps will drop back down. It won't be an immediate flash freeze situation, but high terrain areas will be back below freezing by the mid afternoon and valley areas will be back into the low 30s by evening.

While a few showers can't be ruled out as early as the late evening hours, most of the precip will be arriving well after midnight and into Friday morning. There may be some scattered showers ahead of the front before a well-forced line is expected just ahead of the boundary. CAMs suggest this occurs on Friday morning/early afternoon between about 9 AM and 1 PM. Within this well-forced line, a brief burst of moderate to heavy rainfall is expected. There is a low probability for a rumble of thunder across far southern areas but no surface-based instability is available and even the SPC HREF suggests that any elevated instability is south of the region closer to the coast, according to the MUCAPE values. Behind the well-forced line, there should be a few hour-period of steady light to moderate rainfall before precip tapers off. High terrain areas in the Adirondacks could see this rainfall end as some wet snow with an inch or two of accumulation, but most places will see rain end before temps get cold enough for any wintry precip. All areas should be done with most of the steady precip by the mid afternoon hours, although some lingering light lake enhanced/upslope snow showers are expected for high terrain areas, especially the western Adirondacks. NBM has been very consistent in showing high probabilities for at least 1" of precip (50-90% across nearly the entire area) but low values for 2" or more (with just the Catskills have a slight signal for that). This rainfall will mostly come in a few hours within the well-forced line and steady rainfall behind it.

KEY MESSAGE 2... The rainfall will combine with some snowmelt to runoff into area rivers and streams. High terrain areas may not see much snowmelt, as the snowpack will need to ripen and the rainfall may be absorbed by the snowpack, especially in the Adirondacks and Greens where the snowpack is deeper. Valley areas may start to lose the snowpack, although it has much less water content compared to the high terrain. NOHRSC shows less than 1" of water in most valley areas snowpack at this time and it has already been slowly melting today. As a result, the brief nature of the warmup and limited runoff probably won't be enough to move ice on the larger rivers. However, smaller streams, especially in lower terrain areas, may see some ice movement and river rises. Ice or snow piles may block drainage in urban and low lying areas and the ground is frozen. Based on this, some ponding of water is likely on roadways, in farm fields and other low spots or where infrastructure causes typical issues. The main impacts will be on Friday morning during the most intense rainfall, when rates may exceed 0.25" per hour.

KEY MESSAGE 3... Strong winds are expected both ahead and behind this cold front for tonight through Friday. Southerly winds have already increased across the region, with some gusts being reported around 20 mph. As both the pressure gradient and low level jet increases, winds will increase for tonight into Friday morning. Southerly winds will reach 15 to 30 mph by the late night hours, with gusts in the 40 to 60 mph range. The highest gusts will be across the Taconics, Bennington County Vermont and the Berkshires, where this type of south-southeast flow typically downslopes through the terrain and allows for strong winds on the western slopes. While winds may not always mix down to the moist thermal profile and a low level inversion, there may be periods of gusty winds, especially in between rain showers and for the areas where downsloping occurs. Wind Advisory has been upgraded to a High Wind Warning for the central/northern Taconics, Bennington and Berkshire County, while the Wind Advisory remains in effect elsewhere. Downed trees and power lines are possible due to these winds, especially for those high terrain areas.

As the front crosses, there may be a brief lull for a few hours, but winds will pick up again for Friday afternoon and evening, but from a westerly direction. All areas should widespread windy conditions, with frequent gusts in the 35 to 50 mph range. The peak for these looks to be in the evening when the pressure gradient is strongest and the low level mixing depth increases thanks to strong cold advection behind the system. More downed trees is expected with this surge of wind as well, with winds gradually diminishing for the late night and towards daybreak Saturday.

KEY MESSAGE 4... Behind this system, colder air will be returning to the region for Friday night into Saturday. After morning lows in the mid teens to mid 20s, highs will be in the upper 20s to mid 30s for Saturday. Any lingering wet surfaces Friday night may freeze over, although the wind should help dry things out. A clipper system may bring a few light snow showers for Saturday night into Sunday, but this system appears to be rather moisture starved, with the best dynamics staying north of the region. As a result, snowfall amounts look very light and may just be a fresh coating for the Adirondacks.

However, this system will reinforce the cold air for Monday, with another cold day expected with highs below freezing across most of the entire region. Looking ahead, another northern stream system may bring a widespread light accumulating snow on Tuesday. Guidance has been trending further north with the track of this system, which may limit total precip and models and ensembles only show light QPF at this time. However, enough cold air should be in place that a light accumulation of snow may be possible for many areas, which could be in place for the Christmas holiday. This system will get into better focus over the next few days.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Through 18z Friday...VFR conditions to start the period through early this evening, with just some high level clouds. Then low level stratus clouds will quickly increase as southerly flow strengthens from around 02z-04z at all TAF sites, with MVFR cigs expected. There may be a few light showers from 04z-10z, so will continue to mention PROB30. Steadier rain, occasionally moderate/heavy at times, then develops around 14z-16z Friday just ahead of a cold front approaching from the west. Conditions will deteriorate to IFR at most sites during this time through the end of the TAF period at 18z.

Low level wind shear will be present through the entire 24 hour TAF period, as a strengthening southerly jet moves overhead. Initially through this evening winds at 2000 ft AGL will be around 40-50 kt, increasing to 50-60 kt late tonight through Friday morning. Surface winds will be south-southeast around 3-10 kt into this evening, then steadily increasing tonight into Friday morning to 12-22 kt with gusts of 25-35 kt developing.

Outlook...

Friday Night: Moderate Operational Impact. Windy. Slight Chance of SHSN. Saturday: No Operational Impact. NO SIG WX. Saturday Night: Low Operational Impact. Slight Chance of SHSN. Sunday: Low Operational Impact. Breezy. NO SIG WX. Sunday Night: Low Operational Impact. Breezy. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: Low Operational Impact. Slight Chance of SN. Tuesday: High Operational Impact. Likely RA...SN.

ALY WATCHES/WARNINGS/ADVISORIES

CT...Wind Advisory from 7 PM this evening to 1 AM EST Saturday for CTZ001-013. NY...Wind Advisory from 7 PM this evening to 1 AM EST Saturday for NYZ032-033-038>043-047>053-058>060-063>066-082>084. High Wind Warning from 7 PM this evening to 1 AM EST Saturday for NYZ054-061. MA...High Wind Warning from 7 PM this evening to 1 AM EST Saturday for MAZ001-025. VT...Wind Advisory from 7 PM this evening to 1 AM EST Saturday for VTZ014-015. High Wind Warning from 7 PM this evening to 1 AM EST Saturday for VTZ013.